In the domain of shoulder prostheses, it is known, for example from EP-A-0 299 889, to create a convex articular surface on a glenoid component, while a concave articular surface, of corresponding shape, is formed on a humeral component. The glenoid component of such a surface is very invasive and a subacromial conflict of the humeral component may occur at the end of the movement of abduction.
Furthermore, U.S. Pat. No. 4,846,840 discloses providing, on an intermediate element of a prosthesis, two substantially concentric convex surfaces with a view to their articulation on concave surfaces of corresponding shape, respectively provided on two bones which are to articulate on each other. Such a prosthesis is unstable insofar as no means is provided for avoiding that the two bones cooperating with the intermediate element, move apart from each other. In the event of failure of the articular ligaments, a dislocation cannot be excluded.
It is a more particular object of the invention to overcome these drawbacks by proposing a shoulder- or hip-joint prosthesis which reproduces the anatomical joint while facilitating the abduction of the arm or of the leg, in the absence of the rotator cuffs for the shoulder or of the stabilising structures of the hip.